int readpin=A0;
int v=0;
int wait=500;
int readval;
void setup() {
  // put your setup code here, to run once:
pinMode(readpin, INPUT);
Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
readval=analogRead(readpin);
v=(5./1023.)*readval;
Serial.println(v);
delay(wait);
}